BOSTON (AP) -- By failing to scan security codes in the magnetic
strips on ATM and debit cards, many banks are letting thieves get away
with an increasingly common fraud at a cost of several billion dollars
a year.

A report Tuesday from Gartner Inc., a technology analyst firm,
estimates that 3 million U.S. consumers were victims of ATM and
debit-card fraud in the past year.

The fraud most commonly begins when a criminal engages in "phishing" _
sending a legitimate-seeming e-mail with a link to a phony Web site
that appears to belong to a consumer's bank, Gartner analyst Avivah
Litan believes. The e-mail recipients are asked to give their account
information, including PIN numbers.

With that information "harvested," fraudsters can make their own cards
for automated teller machines and withdraw huge sums.

This should be easily preventable, because the magnetic strips on
cards contain multiple tracks. One track has data such as the user's
name and account number. A second track contains special security
codes that card users don't know. That means the information can't be
squeezed out of them in a phishing attack.

Duplicating the codes would require inside knowledge of a bank's
security procedures, Litan said. (The inclusion of security codes in
records held by a credit and debit card processor, CardSystems
Solutions Inc., made that company's massive data breach disclosed this
spring especially dangerous.)

Surprisingly, Litan said, perhaps half of U.S. financial institutions
have not programmed their ATM systems to check the security codes.
Con artists specifically seek out customers of banks that do not
validate the second track on the strip, she said.

Litan believes many banks simply didn't know about the vulnerability.
Others may have once scanned the codes but stopped because using the
codes requires that customers go to a bank and have an ATM card
rewritten whenever they want to change their PINs.

That was a costly step that many banks figured they could avoid in
pre-phishing days when ATM fraud was rare.